"That's a TBT winch (can't remember what TBT means). Very simple, uses a AMC front spindle/brake system. You should probably look at putting a single tower pulley (like they use on some of the hydraulic PG winches) to guide your line.  A level wind is a big project and expensive. There is a place you can have one made to specific widths, but your looking at least $800 for just the level wind (plus you will need to create a drive system)

You probably want to just get the system running before you make that kind of investment. That said, you should still come up with some sort of steel guide to help manage the rewind of the line. "